1. Field of the Invention
The invention relates to an optical scanning module of a scanner, and more particularly, to an optical scanning module with an adjustable optical path.
2. Description of the Prior Art
Flatbed scanners are widely used with computer systems for converting printed data into image signals. An optical scanning module is the most important component of the flatbed scanner. The scanning module commonly comprises a housing with an opening for receiving light transmitted from a document, an optical sensor installed inside the housing for converting the transmitted light into corresponding image signals, and a plurality of lenses for focusing the transmitted light onto the optical sensor.
The scanning module has a fixed resolution determined by the image amplification of the optical scanning module and the resolving power of the optical sensor. The image amplification of the scanning module is dependent on its lens, the object distance between the document and lens, and the image distance between the lens and optical sensor. If errors of the object and image distances are generated during the installation of the scanning module, the resolution of the scanning module will be affected.
As users demand improved image quality, achieving fewer amplification errors within the scanning module becomes an important issue. Most lenses and reflective mirrors of the scanning module have some production errors, and further positioning errors during installation of components often occur. These errors cause deterioration of the amplification of the scanning module. If error tolerance of lenses and mirrors is very strict, the yield of the scanning module will decrease and calibrations and production costs will increase.